Control method and apparatus



1927. March T. APPLEBY CONTROL ram-non AND APPARATUS Filed July 6. 1921 2 Sheets-Sheet 1 INVENTOR.

' Q ATTORNEY.

, v 1 GI- 11 March 8, 1927. T APPLEBY 9 9 CONTROL METHOD AND APPARATUS Filed July 6. 1921 2 Sheets-Sheet 2 'INVENTOR.

W By k1 ATTORNEY.

Patented Mar. 8,'1927.

UNITED STATES 1,619,911 PATENT OFFICE.

THOMAS APPLEBY, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR OF ONE-THIRD TO CORNELIUS D. EHRE'I, OF PHILADELPHIA, PENNSYLVANIA.

CONTROL METHOD AND APPARATUS.

Application filed July 6, 1921. Serial No. 482,827.

My invention relates to a method of and apparatus for controlling thermionic or electron discharge apparatus utilizable in any suitable relation, including radio telegraphy, telephony or other signaling and systems wherein a conductor or conductors extend between transmitting and receiving stations.

In accordance with my invention, the

potential of the grid-or control electrode of a thermionic or electron discharge device is suitably controlled, as by being made or held to suitable extent negative, without recourse to a battery for such purpose asheretofore commonly practiced, but by suitably correlating the grid or control electrode with another thermionic or electron discharge device and its associated circuit or circuits.

More particularly, in accordance with my invention, the grid is biased as to its potential by recourse to a connection to a suitable point in the grid leak circuit or path of another thermionic or electron discharge device, which latter may be employed in the production of oscillations, such as high frequency oscillations.

In accordance with my invention, the device whose grid potential is so biased may be employed for any suitable purpose, as, for example, a modulator for an oscillationproducing device; or, more particularly, a thermionic or electronic amplifier may have its grid similarly biased as to potential, the amplifier controlling the modulator, which in turn controls the oscillation producer.

My invention resides in the further features of method and apparatus, and modifications, hereinafter described.

For an understanding of my method and for an illustration of some of the forms my apparatus may take, reference is to be had to the accompanying drawing, in which:

Fig. 1 is a diagrammatic view of radio transmitting apparatus embodying my invention.

Fig. 2 is a fragmentary diagrammatic view illustrating a modification.

Fig. 3 is a diagrammatic view of radio transmitting apparatus involving in addition to the modulator, an amplifier.

Referring to Fig. l, V is a thermionic or electron discharge device comprising, for example, a vessel or tube evacuated to an suitable degree, as for example, and pre erably, such degree as permits only of pure p is connected to any suitable source of alter- I nating current, not shown. From the substantially mid point of the secondary a connectlon ls made to' the conductor 1, whereby the cathode 0 is related to both the anode a and grid 9. In circuit with the anode a is a condenser C, which may be of fixed capacity, or, as illustrated, may be variable, the capacity of the condenser C being suitable for ready passage of radio frequency currents but stopping or preventing flow ofthe power current supplied to the apparatus by the conductors 2 and 3. From the condenser connection is made to the oscillation transformer Winding or inductance L to which isconnected also the aforesaid conductor 1, that part of the inductance between the condenser C and conductor 1 be-. ing referably shunted'by a condenser 0 WlllCl may be fixed, or, as indicated, may be variable. The conductor 1 may be connected to earth orcounterpoise capacity E, while the inductance L may be connected to the antenna A, an ammeter or radiation meter W being employed if desired. The grid 9 is connected by conductor 4 to the Inductance L through a condenser G which may be of fixed capacity, or, as indicated,

may be of variable capacity, the capacity nating current, not shown, is connected to 3 the conductors 2 and 3, the conductor 2 being connected to the aforesaid conductor 1 in which is the radio frequency choke coil e,

while conductor 3 is connected through the low frequency or audio frequency choke coil f and thence through the radio frequency choke coil h with the anode a. Bridgin the conductors 2 and 3 is a condenser Ii, preferably of capacity large enough to smooth out the undulations or ripples in the current supplied by the source to the conductors 2 and 3. The circuit arrangements thus far described, in connection with the device V, will be reco ized as those suitable for producing high requency oscillations which will be impressed upon the antenna A or upon any other circuit or system, as for example, upon the conductor or. conductors extending between transmitting and receiving stations in a carrier Wave system.

Associated with the oscillator tube V is a second or modulator tube V which is a thermionic or electron discharge device,

preferably a vacuum tube, the degree of vacuum being of any suitable character, such for example, as hereinbefore referred to. Its anode a is connected *through the choke coil f with the conductor 3, and

through the radio choke it with the anode a of the device V. Its cathode or filament 0 receives current from the aforesaid transformer secondary s, or from any other suitable source. The grid yr of the modulator tube has in its circuit the secondary s of a transformer or induction coil whose primary p isin circuit-with the microphone or other sound-actuated controller M and a source of current, as battery 6- Heretofore it has been common to connect the grid 9 through a battery of primary or secondary cells with the conductor 1, the negative terminal of the battery being connected to the grid 9 and the positive terminal to the conductor 1, for biasing the grid that is, for giving to it or holding it at a suitable negative potential. so arranged, sound waves or speech uttered into the microphone M causes like variation of the potential of the grid 9 so changing the conductivity or impedance of the modulator tube V and so shunting or robhing the oscillation-producing tube V to cause sound wave modulation of the high frequency energy impressed upon the antenna A, for radio telephone purposes.

In accordance with my invention,-however, I dispense wit-h such grid biasing battery and connect the grid 9 by conductor 5 with a suitable point upon the aforesaid resistance B, through which a substantial current is flowing from conductor 1 to the id 9. By this connection, particularly w en the voltage of the circuit 2, 3 which supplies the power is high, for example, 1000 volts when the tube V is of the so-called fifty watt capacity, a suitable lower volta e, for example, 90 or 100 volts, when t e tube V is also of approximately 50 watt capacity, is impressed upon the grid 9 which is so held at corresponding negative potential. While the resistance R is shown as variable, it will be understood that for given circumstances it may be of When fixed value; and while the connection of the conductor 5 is shown to be variable as to its position on the resistance B, it too ma be fixed at a certain suitable point.

etween the conductor 5 and the conductor 1, and to the right of the choke coil e, is a condenser K of relatively large capacity, allowing easy passage of currents of low or audio frequency from the secondary s to the conductor 1, but nevertheless preventing passage of direct current because of the difference of potential between conductors 5 and 1 due to passage of grid leak current through the resistance R. It shall be understood, however, that condenser K may be omitted, as in some cases will be found desirable.

By utteringlsound waves or speech at the microphone the operation will be that above described, the ultimate result being the variation in amplitude in accordance with sound waves or speech of .the sustained high frequency energy delivered to the antenna A or other circuit or conductor.

It will be understood, therefore, that in accordance with my invention the battery for biasing the grid 9 is dispensed with, and the current in the leak circuit from the grid 9 is utilized for biasing the grid 9 In Fig. 2 a modification is shown in that the resistance R ofFig. l'is dispensed with and the conductor 5 connected to the grid g through the radio choke coil d, which,

however, may be short circuited or rendered ineffective by closing the switch '5, in which case the conductor 5 is connected directly to the grid g.

In Fig. 3 the arrangement is similar to that of Fig. 1, except that there is provided in addition an amplifier tube V of-the thermionic or electron discharge type. Its cathode 0 may be supplied by current from a battery 12 or from the same battery I) in the circuit of the microphone M, which in this case is coupled by the transformer p 8 to the circuit of the grid g 9f the amplifier tube V; The anode 0, is connected to the primary p of a transformer whose secondary s is in the circuit of the grid of the modulator tube V The transformer 2 8 may be of the step-down type, though it may also be of the step-up type, according to circumstances. With the amplifier tube V of small capacity, for example, five watts, this transformer may be of the step-down type when the oscillator tube V and modulator V are of larger capacity, as for example, 50 watts or more.

The primary 2 is connected to any suitable point upon t e resistance R connected at one terminal to the conductor 1 and at its other terminal through the choke coil 7 with the conductor 3. Either or both of condensers K and K may be omitted, according to circumstances.

R, and between the As in Fig. 1, the grid g is connected by conductor to a point upon the resistance conductors 1 and 5 is connected the condenser K Similarly, the grid of the amplifier tube V may be biased to suitablevoltage, without employment of a battery, by connecting the grid 9 by conductor 6 with a suitable point upon the resistance R, and a condenser K connected between conductors 1 and 6, the capacity of. the condenser K being suitably large readily to pass currents of low or audio frequency.

In operation the arrangement of Fig- 3 is similar to that described in connection with Fig. 1, except that the microphone controls the amplifier V to cause fluctuations ot the current in its anode circuit in accordance with sound waves or speech, such current traversing the primary eflt'ecting through the secondary 8 corresponding variations of the potential of the grid 9 of the modulator tube V.

In this arrangement the grids of both the modulator and amplifier tubes are biased by voltages due to the current through the grid leak resistance R associated with the oscillator tube V.

It will, of course, be understood that the conductors 5 and 6 of Fig. 3 may be connected with respect to the grid 9 of the oscillator tube V, as indicated in Fig. 2, in which case the conductor 6 may be merely an extension of the conductor 5 or may be considered one and the same conductor connecting to both the grids g and In case it is suitable or desirable that the grids g and 9 shall be biased to or held at the same potential, the conductor 6 may connect directly to the conductor 5, and a separate and independent engagement of the contact 6 with the resistance It may be dispensed with.

As indicated in Figs. 1 and 3, the amounts of the winding or inductance L included in the antenna path, and in the grid and anode circuits of the tube V, are adjustable for (.lctermining the frequency of the oscillations produced and for procuring resonance between the ditierent circuits and paths; and when the condensers C, C and C are variable. they too may serve for like purposes.

For determining when suitable resonance conditions exist, as when the meter \V shows maximum deflection. an anuneter IV in the circuit of the anode a of the tube V may be employed, and the optimum adjustment )1 resonance adjustment or adjustment for maximum energy in the antenna or other ronductor is determinable from the meter W which under the desired circumstances shows a minimum deflection.

W'hile, according to the foregoing descripicn. it is my preference that the biasing of :he grids g and or either of them, is wholly accomplished without recourse to a gridbiasing battery, it will be understood that the biasing electro-motiye-force or electro-motive-forces procured as described by conductors 5 or 5 and 6 may be only a part of the entire biasing electro-motive-force or electro-motive-forces, any other suitable source or sources of electro-motive-force being utilizable in addition, as by using a grid biasing battery or batteries connected in series with the conductor 5 or conductors 5 and 6 and having its or their negative terminal or terminals presented to the grid 9 or grids g and 9 As to the arrangement of Fig. 1, double modulation of the high frequncy oscillations 30 is believed to be effected, one, and probably the principal, modulation being that due to the change of the impedance of the modulator tube V because of changes of potential of its grid g as controlled by the microphone M, and the other modulation is that directly effected by variation of the potentialof the grid 9 of the oscillator V as controlled by the microphone M. i

In Fig. 3 the same situation as to double modulation of the oscillator V by the modulator V is believed to obtain. In addition, however, the amplifier V eiiects direct modulation of the oscillator V by change of potential of its grid 9, and efiects further modulation of the oscillator V by robbing it by that much of the current which traverses the anode circuit of. the amplifier V While I have herein illustrated my invention in connection with radio transmitting apparatus, it shall be understood that my invention is not limited thereto, but comprehends also radio or other receiving apparatus and any other apparatus, whether or not employed for signaling, telegraphy, telephony or the like, but embodying the combinations disclosed and claimed.

For the sake of brevity in the appended claims, the term thermionic is employed in a generic sense to include thermionic and electron discharge devices without regard or limitation to any degree of vacuum, unless otherwise expressed. 1

What I claim is: I

1. The combination with a thermionic oscillator, of a thermionic modulator and a thermionic amplifier, each comprising an anode, grid and cathode, said amplifier controlling the potential of the grid of said modulator, and means for biasing the grid of said amplifier to a potential derived from the grid of said oscillator.

2. The combination with a thermionic os cillator, of a thermionic modulator and a thermionic amplifier, each con'iprising an anode, grid and cathode, said amplifier controlling the potential of the grid of said modulator, means for biasing the grid of said amplifier to a potential derived from the grid of said oscillator, and means for biasing the grid of said modulator to a potential derived from the grid of said oscillator.

3. The combination with a thermionic oscillator comprising an anode, grid and cathode, and a grid leak path, of a thermionic modulator and a thermionic amplifier each comprising an anode, grid and cathode, said amplifier controlling the potential of the grid of said modulator, and means for biasing the grid of said amplifier to a potential derived from the grid leak path of said oscillator.

fl. The combination with a thermionic osclllator comprising an anode, grid and.cathode, anda grid leak path, of a thermionic modulator and a thermionic amplifier each comprising an anode, grid and cathode, said amplifier controlling the potential of the grid of said modulator, means for biasing the grid of said amplifier to apotential de rived irom the grid leak path of said oscillator, and means for biasing the grid of said modulator to a potential derived from said grid leak path of said oscillator.

5. The combination with a thermionic. oscillator, of a thermionic modulator therefor, a thermionic amplifier controlling said modulator, an impedance connected in parallel with the anode circuit of said modulator, and a connection from the anode circuit of said amplifier to said impedance, whereby the anode circuit of said amplifier has iInpressed thereon a lesser voltage than that impressed upon the anode circuit of said modulator.

6. The combination with a thermionic oscillator, of a thermionic modulator therefor, a thermionic amplifier controlling said modulator, a resistance connected in parallel with the anode circuit of said modulator, and a connection from the anode circuit of said amplifier to said rcsistance,whereby the anode circuit of said amplifier has impressed thereon a lesser voltage than that impressed upon the anode circuit of said modulator.

7. The combination with a thermionic oscillator, of a thermionic modulator therefor, a thermionic amplifier controlling said modulator, an impedance connected-in parallel with the anode circuit of said modulator, a connection from the anode circuit of said amplifier to said impedance, whereby the anode circuit of said amplifier has impressed thereon a Lesser "oltage than that impressed upon the anode circuit of said modulator, and a source of current common to the anode circuits of said oscillator and modulator.

8. The combination with a thermionic oscillator, of a thermionic modulator therefor, 21. thermionic amplifier controlling said modulator, a resistance connected in parallel with the anode circuit of said inodulator, a connection from the anode circuit of said amplifier to said resistance, whereby the anode circuit of said amplifier has impressed thereon a lesser voltage than that impressed upon the anode circuit of said modulator, and a source of current common to the anode circuits of said oscillator and modulator.

9. The combination with a thermionic device comprising anode, grid and cathode,

of a second thermionic device comprising anode, grid and cathode, means for biasing the grid of said second device to a potential derived from the grid of said first named device, means for changing the potential of the grid of said second device, and a condenser traversed by currents of low or audio frequency connected in series between the grid and the cathode of said second device.

10. The combination with a thermionic device comprising anode, grid and cathode, of a second thermionic device comprising anode, grid and cathode, means for biasing the grid of said second device to a potential derived from the grid of said first named device, and a condenser traversed by currents of low or audio frequency connected in series between the grids and cathodes of said devices.

11. The combination with a thermionic oscillator, of a thermionic modulator therefor, a thermionic amplifier, each having an anode, grid and cathode, means for biasing the grids of said modulator and amplifier as to their potentials by derivation from the grid of said oscillator, means for changing the potential of the grid of said modulator, a condenser connected between said means and the cathode of said'modulator, means for changing the potential of the grid of said amplifier, and a condenser connected be tween said last named means and the oathode of said amplifier.

12. The combination with a thermionic oscillator, of a thermionic modulator, each comprising an anode, grid and cathode, the anode circuits of said oscillator and modulator being included in parallel paths, a single source of ener for said anode circuits, means for changing the potential of the grids of said oscillator and modulator in opposite senses, a thermionic amplifier comprising an anode, grid and cathode, and means for changing the potential of the grids of saidamplifier and said oscillator in opposite senses.

13. The combination with a thermionic oscillator, of a thermionic modulator a thermionic amplifier, each comprising an anode, grid and cathode, the anode circyits of said oscillator and modulator being included in parallel paths. :1 single source of energy for said anode circuits, means for biasing the grids of said modulator and amplifier to potentials derived from the grid of said oscillator, and means for changing the potential of the grids of said oscillator and amplifier in opposite senses.

14. The combination with a thermionic oscillator, .of a thermionic modulator, a thermionic amplifier, each having an anode, grid and cathode. the anode circuits of said oscillator, modulator and amplifier being connected in parallel aths, a source of current common to said anode circuits, and means for changing the potentials of the grids of said amplifier and modulator in the same sense and the potential of the grid of said oscillator in opposite-sense.

15. The combination with a thermionic oscillator, of a thermionic modulator, said oscillator having a grid leak containing a resistance, a connection from said resistance to the grid of said modulator, means for controlling the potential of the grid of said modulator in accordance with sound waves, and a condenser connected across a portion of said resistance and having a capacity suitable for passing current of sound wave frequencies.

16. The combination with a thermionic oscillator comprising a thermionic device having an anode, grid and cathode, a coupling between the grid and'anode circuits, a condenser in the connection between the grid and the coupling, a second thermionic device having anode grid and cathode, and a connection from a point between said condenser and the grid of said first named ther mionic device to the grid of said second thermionic device.

17. The combination .with a thermionic oscillator, ofa thermionic modulator and a thermionic amplifier, each comprising an anode, grid and cathode, said amplifier controlling the potential of the grid of said modulator, and means for biasing the grid of said amplifier to a potential derived from the grid of said oscillator.

18. The combination with a thermionic oscillator, of a thermionic modulator and a thermionic amplifier, each comprising an anode, grid and cathode, said amplifier controlling the potential of the grid of said modulator, the grid of said oscillator having a leak path. and means for biasing the grid of said amplifier to a potential derived from said leak path.

19. The combination with a thermionic oscillator, of a thermionic modulator and a thermionic amplifier, each comprising an anode, grid and cathode, said amplifier controlling the potential or the grid'of said modulator, and means for influencing, the potential of the grid of said modulator and the potential of the grid of said amplifier by the grid of said oscillator.

20. The combination with a thermionic oscillator. of a thermionic modulator and a thermionic amplifier, each comprising an anode, grid and cathode, said amplifier controlling the potential of the grid of said modulator, the grid of said oscillator having means for biasing the of energy for said a leak path, and means for influencing the potential of the grid of said modulator and the potential of the grid of said amplifier by said leak path.

21. The combination with a thermionic oscillator. of a thermionic modulator and a thermionic amplifier, each comprising an anode, grid and cathode, the anode circuits of said oscillator and modulator being included in parallel paths,.a common source of energy for said anode circuits, the anode circuit of said amplifier controlling the potential of the grid of said modulator. and grid of said amplifier to a potential derived from the grid of said oscillator, v

22. The combination with a thermionic oscillator, of a thermionic modulator and a thermionic amplifier, each comprising an anode, grid and cathode, the anode circuits of said oscillator and modulator being included in parallel paths, a common source of energy for said anode circuits, the anode circuit of said amplifier controlling the po tential of the grid of said modulator, and

means for influencing the potential of the grid of saidmodulator and the potential of the grid of said amplifier by the grid of'said oscillator.

23.,The combination with a thermionic oscillator, of a thermionic modulator and a thermionic amplifier, each comprising an anode, grid and cathode, the anode circuits of said oscillator and modulator being included in parallel paths, a common source of energy for said anode circuits, the anode circuit of said amplifier controlling the potential of the grid of said modulator, a leak path for the grid of said oscillator, and means fol-biasing the grid of said amplifier to a potential derived from said leak path.

24. The combination with a thermionic oscillator, of a thermionic modulator and a thermionic amplifier, each comprising an anode, grid and cathode, the anode circuits of said oscillator and modulator being included in parallel paths, a common source anode circuits, the anode circuit of said amplifier controlling the potential of the grid of said modulator, a leak path for the grid of said oscillator, and means for influencing the potential of the grid of said modulator and the potential of the grid of said 7 25. The'combination with a thermionic oscillator, of a thermionic modulator and a thermionic amplifier, each comprising an anode, grid and cathode, said modulator controlling the production of oscillations by said oscillator, said amplifier controlling the potentialof the grid of said modulator, and means for biasing the grids of said modulator and amplifier to different potentials from the grid of said oscillator.

26. The combination with a thermionic osamplifier by said leak path.

cilator, of a thermionic modulator and a thermionic amplifier, each comprising an anode, grid and cathode, said modulator controlling the production of oscillations by said oscillator, said amplifier controlling the potential of the grid of said modulator, an impedance connected to the grid of said oscillator, and connectionsi from different points on said impedance to the grids of said modulator and amplifier.

27. The combination with a thermionic oscillator comprising an anode, cathode and grid, of means for coupling the anode and grid circuits for producing oscillations, a

path from grid to cathode including an in- It said second device for influencing the potential' thereof.

In testimony whereof I have hereunto affixed my signature this 1st day of July, 1921.

' THOMAS APPLEBY. 

